Traditional manual bicycle operations involve the utilization of a chain to allow for transfer of power from a pedal gear to a wheel gear to provide the necessary rotational energy for vehicle propulsion. The chain component drives a rear wheel in such an operation while the front wheel is present for balance and steering purposes with a handlebar configuration for control. Recumbent bicycles have been available within the industry for quite some time, providing a unique alternative to the upright cycling position with resultant potential exercise workout improvements for such users. While recumbent cycle designs generally position a pedal assembly above and/or ahead of a front wheel, said front wheel is generally not both steered and driven, due to limitations of the applied transmission technologies.
There have been some developments that have taken into consideration the capabilities of epicyclic gear configurations for power transmission to a steered front wheel within a cycling operation. To that end, such devices tend to utilize a gear train to transmit power across a plane of steering rotation by use of a sun gear coaxial to a steering axis. In principle, this arrangement may allow relatively unrestricted steering, with a further benefit of a high efficiency spur gear transmission. A particular configuration may solve this problem with minimal steering interference under worst-case road-load conditions by using a two-stage transmission system. A first transmission stage, a fixed transmission assembly attached to a vehicle frame, derives input power from a conventional pedal crank and reduces the torque for output to a second stage. A second transmission stage, a movable transmission assembly comprising a movable wheel support structure, such as a front fork steered by conventional handlebars, receives the low-torque power through an epicyclic gear train coaxial to the steering axis, and multiplies the torque as needed to drive an attached, steerable wheel. By this means, a maximum torque transmitted across a plane of steering between fixed and movable transmission assemblies is limited to avoid undesirable steering interference. A torque thus applied to drive a steered front wheel may be further adjusted, if desired, by incorporation of a conventional, multi-speed, planetary transmission located within the wheel hub, for instance, achieving an overall function analogous to the multiple chainwheels and sprockets employed on conventional cycles. Such devices, while effectively achieving the stated function, may benefit from further improvements as disclosed herein.
The ability to accord such a transmission assembly within a structure that is configured for facilitated manufacture and repair, at least, would prove beneficial for reasons of improved economy, quality and reliability. Unfortunately, there is nothing within this art that teaches such an aspect as it concerns torque modifying assemblies and structures. In other words, a modular drive unit for such a cycle device with a torque modifying assembly including a pedal component, in addition to the base torque reducing/multiplying assembly, would allow for greater reliability and reduction in complexity during manufacture, at least. To date, however, as this type of transmission has yet to be accorded this industry prior to such disclosure, the contemplation of any type of modular configuration housing such a component, as well as the pedals themselves, is lacking within the industry.
A means to provide for indications of reaching and limiting torque level maxima, without the need for operator determination and action has not been considered in prior art, despite the enhancement such a function may provide to such manual vehicles. Another potential improvement resides in this cycle area with the utilization and availability of means for detaching modular transmission assemblies on demand and ensuring the interface gears will realign in proper mesh upon reengagement of all contacting and moving parts. Such a gear lash adjustment thus would provide a far greater reliability without fear of gear stripping during, or repositioning error prior to, actual utilization. Such would, again, be greatly and highly desired within this industry. Lastly, the ability to provide such an overall transmission assembly housed within or adjacent to a shock-absorbing suspension of the steerable front wheel would also be desirable in this industry. Such a structural component could accord balanced operations and reduced stresses to the vehicle when operated over different types of terrain, for instance. Nothing, however, within the prior art appears to provide or permit such a unique possible device, particularly as it concerns any type of housing for a transmission assembly. Basically, there remains a rather large amount of significant cycle device components that have yet to be brought to market for structures including recumbent structures. Thus, much remains desired within this commercial space for improvements.